1. Field of the Invention
The invention is directed to an antenna assembly for use in an electronic apparatus. More particularly, this invention is directed to a thin antenna for use with a portable electronic apparatus, such as a cordless telephone, and its method of manufacture.
2. Description of Related Art
Antenna elements in cordless telephones are typically either a heavy wire coiled like a spring or a small wire that is wrapped around a separate wire core. Other known antenna assemblies can be constructed as a braided cable or a center conductor of a coaxial cable.
A protective cover is generally provided over the antenna assembly. The cover is typically made of plastic and either molded over the antenna lead or attached to the antenna lead by separate fasteners, crimping or gluing. However, such covers do not adequately protect the antenna lead since these covers are directly attached to the antenna. For example, when a force is applied to the prior art covers of an antenna assembly, that force will be directly transmitted to the antenna assembly and/or internal circuitry of an electronic apparatus.
The prior art antenna assemblies discussed above have further drawbacks including additional required parts that make assembly more complicated and expensive. For example, conventional antenna assemblies cannot be connected directly to circuitry of a printed circuit board of an associated electronic apparatus. Conventional antenna assemblies require additional connection parts and/or supplemental connection parts, such as stamped or die cast brackets, wires and supports. These must be soldered, screwed or otherwise connected to a printed circuit board of the electronic apparatus. Further, they usually require at least one additional connection part to attach them to an actual antenna lead. Of course, this increases the cost of the antenna assembly, requires more manufacturing steps to assemble the antenna to the electronic device and complicates the overall antenna assembly. Further, the additional parts and connections introduce additional failure locations in the antenna assembly and associated electronic apparatus.
Another drawback in conventional antenna assemblies is that a separate ground lead must be provided when the physical length of the antenna is longer than its electrical length. Attempts to overcome this and other disadvantages have included covering a part of the antenna with a braided sheath, such as the outer conductor of a coaxial cable. However, supplemental parts are then required to connect this ground to the printed circuit board. Further, an insulator is required to separate the ground from the driven lead of the antenna assembly. This, of course, also increases the cost of the antenna assembly, adds steps to the manufacturing process and provides additional failure points in the antenna assembly.
A further drawback in conventional antenna assemblies is that these assemblies and covers rely on the antenna lead itself for mechanical strength. Since the antenna cover is attached to the antenna lead, any force, stress or strain applied to the cover is transferred directly to the antenna lead. In turn, the force is transferred directly to the printed circuit board of the associated electrical apparatus. This, of course, leads to breakage of the antenna leads and printed circuit board of the associated electrical apparatus and/or deterioration of the operation of the electrical apparatus.